NATO Science for Peace and Security Series C: Environmental Security, Uncertainties in Environmental Modelling and Consequences for Policy Making, pp.3-26
This paper analyses the major features of spatially explicit and lumped hydro-logical models based on two case studies. For two different catchments in West Africa and Germany model intercomparison studies were performed to reveal the model structure and spatial resolution dependent advantages and disadvantages of the different model types. It can be shown that different model types (lumped versus distributed models and conceptual versus physically based models) have benefits and drawbacks. But all model predictions of different type models contain some valuable information when used for the simulation of catchment water fluxes. Using local scale data from intense field experiments, the sophisticated and spatially explicit models simulate stream flow of a West African catchment with the same performance obtained by lumped models that can be calibrated more efficiently. In addition, the spatially explicit models generate plausible spatial patterns of state variables and processes which can be validated by additional observations. Using regional scale available data to predict stream flow of a German catchment, the simpler models tend to perform better in both calibration and validation periods. But while all models tend to show improved performance during the less extreme validation period, this improvement is greatest for some of the more complex models. Applying the same models (of different model types) to three land use change scenarios, there is broad agreement among the models on the expected hydrological change. This suggests that we can predict with some confidence the direction and magnitude of stream flow changes associated with land use change, especially by combining the predictions of different model types. As a short outlook, it is shown that a simple multi-model application offers a sound basis for multi-model ensembles that are based on a technique currently applied successfully in many atmospheric forecast and scenario studies.
Environment ; Math. Appl. in Environmental Science ; Environmental Law/Policy/Ecojustice ; Environmental Management ; Climate Change ; Soil Science & Conservation ; Engineering ; Environmental Sciences